package leetCode.trieNode;

public class Class01_TrieTree {
    public static class TrieNode{
        public int pass;
        public int end;
        public TrieNode[] nexts;
        public TrieNode(){
            pass  =0;
            end = 0;
            nexts = new TrieNode[26];
        }
    }
    public static class Trie{
        private TrieNode root;
        public Trie(){
            root = new TrieNode();
        }
        public void insert(String word){
            if(word == null){
                return;
            }
            char chs[] = word.toCharArray();
            TrieNode node = root;
            node.pass++;
            int index = 0;
            for(int i = 0;i<chs.length;i++){
                index = chs[i]-'a';
                if(node.nexts[index]==null){
                    node.nexts[index] = new TrieNode();
                }
                node = node.nexts[index];
                node.pass++;
            }
            node.end++;
        }
        //word这个单词之前加入过几次
        public int search(String word){
            if(word==null){
                return 0;
            }
            char[] chs = word.toCharArray();
            TrieNode node =root;
            int index = 0;
            for(int i = 0;i<chs.length;i++){
                index = chs[i]-'a';
                if(node.nexts[index]==null){
                    return 0;
                }
                node = node.nexts[index];
            }
            return node.end;
        }
        //所有加入的字符串中，有几个是以pre这个字符串作为前缀的
        public int preNumber(String pre){
            if(pre == null){
                return 0;
            }
            char[] chs = pre.toCharArray();
            TrieNode node = root;
            int index = 0;
            for(int i = 0;i<chs.length;i++){
                index = chs[i]-'a';
                if(node.nexts[index] == null){
                    return  0;
                }
                node = node.nexts[index];
            }
            return node.pass;
        }
        //删除word这个单词
        public void delete(String  word){
            if(search(word)!=0){//word数量不等于0才能删除
                char [] chs = word.toCharArray();
                TrieNode node = root;
                node.pass--;
                int index = 0;
                for(int i = 0;i<chs.length;i++){
                    if(--node.nexts[index].pass==0){
                        node.nexts[index] = null;
                        return ;
                    }
                    node = node.nexts[index];
                }
                node.end--;
            }
        }

    }
}
